Genetic Engineering

whooshdisguisingBiotechnology

Dec 14, 2012 (5 years and 22 days ago)

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DNA Fingerprinting

Comparing DNA samples

using gel electrophoresis

How is DNA fingerprinting
technology useful?


Food identification


Mystery meat


Endangered species


Forensics


Crime scenes


Overturning erroneous convictions


Human remains



Paternity/maternity


Child support


Immigration


Health and medicine


Genetic disorders


Bone marrow transplants


Identifying pathogens

How can we examine
DNA to look for
similarities and
differences?


Electrophoresis


“carry with electricity”

DNA samples
from crime
scene and
suspects


Bacteria provide

tools to cut DNA


“DNA scissors” produced by bacteria


Adaptation to protect bacteria against viruses

Restriction Enzymes


More than 3000 known restriction enzymes,
or “endonucleases”


Each cuts at a specific DNA sequence called
a
restriction site
.


Restriction sites are palindromes

How do restriction enzymes
work?



What happens when we cut all
DNA samples with the same
restriction enzyme?

1
-------------
GAATTC
-----------------------------

2
---
GAATTC
--------------------
GAATTC
-------

3
---
GAATTC
----
GAATTC
----
GAATTC
-------

4
-----------------------------
GAATTC
-------------

1
-------------
GA ATTC
-----------------------------


2
---
GA ATTC
--------------------
GA ATTC
-------

3
---
GA ATTC
----
GA ATTC
----
GA ATTC
-------

4
---------------------------------
GA ATTC
---------

Electrophoresis animation

Click here

How will the fragments appear
in a gel?

1
-------------
GA ATTC
-----------------------------


2
---
GA ATTC
--------------------
GA ATTC
-------

3
---
GA ATTC
----
GA ATTC
----
GA ATTC
-------

4
---------------------------------
GA ATTC
---------

Electrophoresis Procedure


Cut DNA samples with restriction enzymes


Add loading dye to samples


Load samples in gel and apply charge


DNA separates by size (small=fast)


Stain DNA in the gel


Bands appear where same
-
sized
fragments are located, forming a pattern


Compare patterns to find matches


Pipette technique


Find well opening with tip


Depress plunger s..l..o..w..l..y…


Watch for air bubbles


New tip for each sample!

The disposable graduated pipette